Is the ItaliaPass and InterRail pass the same?

I am in the process of purchasing a train ticket online. So, in relation to "Passholder Reservation", is the ItaliaPass and InterRail pass considered to be the same? Also, what does the following "Passholder Reservation" statement actually mean, i.e. "This fare is ONLY for a seat reservation and must used in conjunction with Railway passes where compulsory seat reservations are required. When purchasing a seat reservation, Passholders must purchase the same class of seating as the railway pass"